NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Dissecting the EUV spectrum of CapellaExtreme ultraviolet spectra of Capella, obtained at various orbital phases over the past two years by the EUVE satellite, show strong emission lines from a continuous distribution of temperatures (approximately 10(exp 5 -10(exp 7.3) K). In addition to the strong He II lambda 303.8, the spectra are dominated by emission lines of highly ionized iron. Strong lines of Fe IX, XV, XVI, and XVIII-XXIV are used to construct emission measure distributions for the individual pointings, which show several striking features, including a minimum near 10(exp 6) K and a local maximum at 10(exp 6.8) K. Furthermore, intensities of the highest temperature lines (Te is greater than 10(exp 7) K) show variations (factors of 2-3) at different orbital phases, while the lower temperature Fe lines show variations of about 30% or less. The low variability of most of the strong low temperature features motivates a detailed analysis of the summed spectrum. With approximately 280 ksec of total exposure time, we have measured over 200 emission features with S/N greater than or equal to 3.0 in the summed spectrum. We report here initial results from the analysis of this spectrum. We can now identify lines of Fe VIII and X-XIV, as well as a number of electron density and abundance diagnostic lines. We also report here the first direct measurement of the continuum flux around approximately 100 A in a cool star atmosphere with EUVE. The continuum flux can be predicted from the emission measure model based on Fe line emission, and demonstrates that the Fe/H abundance ratio is dose to the solar photospheric value.
Document ID
19960007143
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Brickhouse, Nancy S.
(Smithsonian Astrophysical Observatory Cambridge, MA, United States)
Date Acquired
September 6, 2013
Publication Date
August 1, 1995
Publication Information
Publication: Smithsonian Astrophysical Observatory,
Subject Category
Astrophysics
Accession Number
96N14308
Funding Number(s)
CONTRACT_GRANT: NAGW-528
CONTRACT_GRANT: NAG5-2330
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available